Optical Spectrum Analyzers (OSAs) can be used to measure spectral output of an optical transmitter. In some examples, OSAs measure the magnitude and wavelength of a multi-channel signal across a full wavelength range of the OSA. Optical transmitters are sometimes evaluated to verify that the performance of the optical transmitter is within specification or design limits for a particular application or optical receiver. For instance, various parameters can be measured, such as the center wavelength emitted from the optical transmitter, the presence and amplitude of any side-mode effects (spurs), the amplitude of the emitted light, or other parameters. Many OSAs are standalone benchtop or rack mounted devices including optical detectors. Measurement of an optical sample can be performed in a manufacturing environment, at an optical transmitter supplier, or in the field, to name a few examples.